* McFaul the architect of Obama's Russia "reset"
* Faced criticism from Russia during turbulent tenure
* Cites accomplishments such as nuclear arms treaty
U.S. Ambassador Michael McFaul, who engineered Washington's "reset" of relations with Moscow but riled Russia during his tenure as envoy, said on Tuesday he would soon leave his posting and the administration of President Barack Obama.
McFaul helped Obama improve ties with Russia during his first term but was clouded by controversy from the start of his stint as envoy after Vladimir Putin, campaigning to regain the presidency in 2012, accused Washington of stirring up protests.
McFaul cited family reasons for his departure, saying his wife and sons had moved back to California last summer and that he would be based for the time being at Stanford University, where he taught before Obama brought him to Washington in 2009.
"After more than five years working for the Obama administration, it is time to go home," McFaul, 50, said in a lengthy entry on his blog. "I will leave Russia reluctantly. I love this job."
A meeting with rights activists and opposition leaders during McFaul's first week in Moscow drew criticism from Russian officials and particularly the state media, which often have portrayed him as seeking to foment revolution.
But it was McFaul's manner, as much as the U.S. policies he pursued, that frequently rubbed Russian officials the wrong way. The ebullient native of the western frontier state of Montana broke the mould of restrained diplomacy, using social media and speeches to students to get his messages across.
Foreign Minister Sergei Lavrov once accused McFaul of arrogance, and the ministry said he had stepped "far beyond the boundaries of diplomatic etiquette" when he said Russia had offered Kyrgyzstan a bribe to kick the United States out of a transit facility used to support operations in Afghanistan.
"We've had a difficult period. We've had issues that have been tough," McFaul told reporters later on Tuesday. But he said there was no political reason for his departure and that it was not a reflection of the state of Russian-American ties.
A Russian speaker and expert, McFaul was Obama's top adviser on Moscow during the "reset", which improved relations that had become increasingly strained during the administration of George W. Bush and hit a low with Russia's war against Georgia in 2008.
FRICTION INCREASED AFTER PUTIN RETURNED
McFaul said he would go with "a sense of accomplishment", citing the new START nuclear arms limitation pact, cooperation on Afghanistan and Russia's entry into the World Trade Organisation as achievements reached since he joined Obama.
"President Obama is deeply grateful for Ambassador McFaul's extraordinary service over the last five years," White House deputy national security adviser Ben Rhodes said, adding he "helped shape policies that advanced America's interests.
"Moreover, Mike has been tireless in advocating for the universal values that America stands for around the world, reaching out to civil society, and recognising the right of every voice to be heard," Rhodes said.
That advocacy found a relatively cordial reception under former President Dmitry Medvedev but relations soured again when Putin, who has frequently accused the United States of trying to undermine Russia, returned to the Kremlin.
Moscow has ejected the U.S. Agency for International Development, saying it tried to sway elections. It has also barred Americans from adopting Russian children in response to a U.S. law blacklisting Russians deemed involved in abuses including the death of whistleblowing lawyer Sergei Magnitsky.
Putin snubbed a G8 summit hosted by Obama in 2012 and Obama called off a Moscow meeting with Putin last year after Russia granted asylum to fugitive American Edward Snowden.
McFaul fast became a prime target of anti-American rhetoric in the Russian media. He was often shadowed by reporters from a Kremlin-friendly TV station, prompting him to wonder publicly where the media had got a hold of his schedule.
In his blog, McFaul said he would continue to work on "some specific projects" for Obama and his administration and that "part of me - an emotional part, an intellectual part, a spiritual part - will always remain in Russia."